热氧老化对碳纤维织物增强聚合物基复合材料弯曲性能的影响

为了探索增强体结构对碳纤维增强聚合物基复合材料(CF-PMCs)热氧老化后弯曲性能的影响,对三维四向编织碳纤维/环氧复合材料(简称为三维编织复合材料)和层合平纹碳布/环氧复合材料(简称为层合复合材料)的热氧老化性能进行了研究。利用FTIR、老化失重、弯曲测试和SEM等手段分析了热氧老化前后的试样。结果表明:热氧老化导致基体树脂的氧化断链以及纤维/基体界面结合力的退化是两种复合材料弯曲强度和弯曲模量下降的原因,弯曲强度比弯曲模量更容易受热氧老化的影响。在相同的热氧老化条件下,层合复合材料的热氧老化失重大于三维编织复合材料的,而三维编织复合材料的弯曲强度和弯曲模量保留率均大于层合复合材料的。在140℃下老化1 200h后,层合复合材料的弯曲强度和弯曲模量保留率分别为74.7%和88.3%,而对应的三维编织复合材料的分别为79.4%和91.5%。因此,采用三维编织预制件作为CF-PMCs的增强体是一种有效的提高其热氧稳定性的方法。

Effects of thermo-oxidative aging on flexural properties of carbon fiber fabric reinforced polymer matrix composites

In order to explore the reinforced structure effects on the flexural strength of carbon fiber reinforced polymer matrix composites (CF-PMCs) after thermal-oxidative aging, the thermal-oxidative aging properties of 3D four-directional braided carbon fiber/epoxy composites (3D braided composites for short) and laminated plain weave carbon fabric/epoxy composites (laminated composites for short) were studied. The samples before and after thermos-oxidative aging were analyzed by means of FTIR, aging mass loss, bending test and SEM. The results indicate that the oxidation chain scissions of matrix resin and the degradation of the bonding force of fiber/matrix interface caused by thermal-oxidative aging are the reasons for the decrease of the flexural strength and flexural modulus of the two kinds of composites. Flexural strength is more easily affected by thermal-oxidative aging than flexural modulus. Under the same thermal-oxidative aging conditions, the thermal-oxidative aging mass loss of laminated composites is larger than that of 3D braided composites, but the flexural strength and flexural modulus retention rates of the 3D braided composites are greater than those of laminated composites. After age at 140 ℃ for 1 200 h, the flexural strength and flexural modulus retention rates of laminated composites are 74.7% and 88.3%, respectively, and those of corresponding 3D braided composites are 79.4% and 91.5%, respectively. Therefore, adopting 3D braided preform as the reinforcement of CF-PMCs is an effective way to improve the thermo-oxidative stability.